Our research objective is the composite of several objectives: We wish to prepare reconstituted membrane vesicles ("synthetic cells") having precisely defined chemical compositions, and physical properties. These synthetic cells are designed to mimic real biological cells in respect to their highly specific interactions with other cells, especially cells of the immune system (macrophages, T-cells, B-cells, neutrophils, mast cells). The essential question is, when a cell of the immune system recognizes and treates another cell as "foreign," or "non-self," just what are the molecular properties of the target that are necessary and sufficient for this recognition? And when a "foreign" or "non-self" cell is attacked, what is the mechanism of killing? We propose to answer these questions using appropriately fabricated synthetic cells.